129088Smarkm/* 229088Smarkm * Copyright (c) 1988, 1993 329088Smarkm * The Regents of the University of California. All rights reserved. 429088Smarkm * 529088Smarkm * Redistribution and use in source and binary forms, with or without 629088Smarkm * modification, are permitted provided that the following conditions 729088Smarkm * are met: 829088Smarkm * 1. Redistributions of source code must retain the above copyright 929088Smarkm * notice, this list of conditions and the following disclaimer. 1029088Smarkm * 2. Redistributions in binary form must reproduce the above copyright 1129088Smarkm * notice, this list of conditions and the following disclaimer in the 1229088Smarkm * documentation and/or other materials provided with the distribution. 13351432Semaste * 3. Neither the name of the University nor the names of its contributors 1429088Smarkm * may be used to endorse or promote products derived from this software 1529088Smarkm * without specific prior written permission. 1629088Smarkm * 1729088Smarkm * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 1829088Smarkm * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1929088Smarkm * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2029088Smarkm * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 2129088Smarkm * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2229088Smarkm * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2329088Smarkm * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2429088Smarkm * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2529088Smarkm * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2629088Smarkm * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2729088Smarkm * SUCH DAMAGE. 2829088Smarkm */ 2929088Smarkm 30114630Sobrien#if 0 3129088Smarkm#ifndef lint 3229181Smarkmstatic const char sccsid[] = "@(#)ring.c 8.2 (Berkeley) 5/30/95"; 3363248Speter#endif 34114630Sobrien#endif 35114630Sobrien#include <sys/cdefs.h> 36114630Sobrien__FBSDID("$FreeBSD: stable/11/contrib/telnet/telnet/ring.c 351432 2019-08-23 17:40:47Z emaste $"); 3729088Smarkm 3829088Smarkm/* 3929088Smarkm * This defines a structure for a ring buffer. 4029088Smarkm * 4129088Smarkm * The circular buffer has two parts: 4229088Smarkm *((( 4329088Smarkm * full: [consume, supply) 4429088Smarkm * empty: [supply, consume) 4529088Smarkm *]]] 4629088Smarkm * 4729088Smarkm */ 4829088Smarkm 4981965Smarkm#include <errno.h> 5029088Smarkm#include <stdio.h> 5129181Smarkm#include <string.h> 5229088Smarkm 5329088Smarkm#ifdef size_t 5429088Smarkm#undef size_t 5529088Smarkm#endif 5629088Smarkm 5729088Smarkm#include <sys/types.h> 5829088Smarkm#ifndef FILIO_H 5929088Smarkm#include <sys/ioctl.h> 6029088Smarkm#endif 6129088Smarkm#include <sys/socket.h> 6229088Smarkm 6329088Smarkm#include "ring.h" 6429088Smarkm#include "general.h" 6529088Smarkm 6629088Smarkm/* Internal macros */ 6729088Smarkm 6829088Smarkm#if !defined(MIN) 6929088Smarkm#define MIN(a,b) (((a)<(b))? (a):(b)) 7029088Smarkm#endif /* !defined(MIN) */ 7129088Smarkm 7229088Smarkm#define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ 7329088Smarkm (a)-(b): (((a)-(b))+(d)->size)) 7429088Smarkm 7529088Smarkm#define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ 7629088Smarkm (a)+(c) : (((a)+(c))-(d)->size)) 7729088Smarkm 7829088Smarkm#define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ 7929088Smarkm (a)-(c) : (((a)-(c))-(d)->size)) 8029088Smarkm 8129088Smarkm 8229088Smarkm/* 8329088Smarkm * The following is a clock, used to determine full, empty, etc. 8429088Smarkm * 8529088Smarkm * There is some trickiness here. Since the ring buffers are initialized 8629088Smarkm * to ZERO on allocation, we need to make sure, when interpreting the 8729088Smarkm * clock, that when the times are EQUAL, then the buffer is FULL. 8829088Smarkm */ 8929088Smarkmstatic u_long ring_clock = 0; 9029088Smarkm 9129088Smarkm 9229088Smarkm#define ring_empty(d) (((d)->consume == (d)->supply) && \ 9329088Smarkm ((d)->consumetime >= (d)->supplytime)) 9429088Smarkm#define ring_full(d) (((d)->supply == (d)->consume) && \ 9529088Smarkm ((d)->supplytime > (d)->consumetime)) 9629088Smarkm 9729088Smarkm/* Buffer state transition routines */ 9829088Smarkm 9987139Smarkmint 10087139Smarkmring_init(Ring *ring, unsigned char *buffer, int count) 10129088Smarkm{ 10229088Smarkm memset((char *)ring, 0, sizeof *ring); 10329088Smarkm 10429088Smarkm ring->size = count; 10529088Smarkm 10629088Smarkm ring->supply = ring->consume = ring->bottom = buffer; 10729088Smarkm 10829088Smarkm ring->top = ring->bottom+ring->size; 10929088Smarkm 11029088Smarkm#ifdef ENCRYPTION 11129088Smarkm ring->clearto = 0; 11229088Smarkm#endif /* ENCRYPTION */ 11329088Smarkm 11429088Smarkm return 1; 11529088Smarkm} 11629088Smarkm 11729088Smarkm/* Mark routines */ 11829088Smarkm 11929088Smarkm/* 12029088Smarkm * Mark the most recently supplied byte. 12129088Smarkm */ 12229088Smarkm 12387139Smarkmvoid 12487139Smarkmring_mark(Ring *ring) 12529088Smarkm{ 12629088Smarkm ring->mark = ring_decrement(ring, ring->supply, 1); 12729088Smarkm} 12829088Smarkm 12929088Smarkm/* 13029088Smarkm * Is the ring pointing to the mark? 13129088Smarkm */ 13229088Smarkm 13387139Smarkmint 13487139Smarkmring_at_mark(Ring *ring) 13529088Smarkm{ 13629088Smarkm if (ring->mark == ring->consume) { 13729088Smarkm return 1; 13829088Smarkm } else { 13929088Smarkm return 0; 14029088Smarkm } 14129088Smarkm} 14229088Smarkm 14329088Smarkm/* 14429088Smarkm * Clear any mark set on the ring. 14529088Smarkm */ 14629088Smarkm 14787139Smarkmvoid 14887139Smarkmring_clear_mark(Ring *ring) 14929088Smarkm{ 15029088Smarkm ring->mark = 0; 15129088Smarkm} 15229088Smarkm 15329088Smarkm/* 15429088Smarkm * Add characters from current segment to ring buffer. 15529088Smarkm */ 15687139Smarkmvoid 15787139Smarkmring_supplied(Ring *ring, int count) 15829088Smarkm{ 15929088Smarkm ring->supply = ring_increment(ring, ring->supply, count); 16029088Smarkm ring->supplytime = ++ring_clock; 16129088Smarkm} 16229088Smarkm 16329088Smarkm/* 16429088Smarkm * We have just consumed "c" bytes. 16529088Smarkm */ 16687139Smarkmvoid 16787139Smarkmring_consumed(Ring *ring, int count) 16829088Smarkm{ 16929088Smarkm if (count == 0) /* don't update anything */ 17029088Smarkm return; 17129088Smarkm 17229088Smarkm if (ring->mark && 17329088Smarkm (ring_subtract(ring, ring->mark, ring->consume) < count)) { 17429088Smarkm ring->mark = 0; 17529088Smarkm } 17629088Smarkm#ifdef ENCRYPTION 17729088Smarkm if (ring->consume < ring->clearto && 17829088Smarkm ring->clearto <= ring->consume + count) 17929088Smarkm ring->clearto = 0; 18029088Smarkm else if (ring->consume + count > ring->top && 18129088Smarkm ring->bottom <= ring->clearto && 18229088Smarkm ring->bottom + ((ring->consume + count) - ring->top)) 18329088Smarkm ring->clearto = 0; 18429088Smarkm#endif /* ENCRYPTION */ 18529088Smarkm ring->consume = ring_increment(ring, ring->consume, count); 18629088Smarkm ring->consumetime = ++ring_clock; 18729088Smarkm /* 18829088Smarkm * Try to encourage "ring_empty_consecutive()" to be large. 18929088Smarkm */ 19029088Smarkm if (ring_empty(ring)) { 19129088Smarkm ring->consume = ring->supply = ring->bottom; 19229088Smarkm } 19329088Smarkm} 19429088Smarkm 19529088Smarkm 19629088Smarkm 19729088Smarkm/* Buffer state query routines */ 19829088Smarkm 19929088Smarkm 20029088Smarkm/* Number of bytes that may be supplied */ 20187139Smarkmint 20287139Smarkmring_empty_count(Ring *ring) 20329088Smarkm{ 20429088Smarkm if (ring_empty(ring)) { /* if empty */ 20529088Smarkm return ring->size; 20629088Smarkm } else { 20729088Smarkm return ring_subtract(ring, ring->consume, ring->supply); 20829088Smarkm } 20929088Smarkm} 21029088Smarkm 21129088Smarkm/* number of CONSECUTIVE bytes that may be supplied */ 21287139Smarkmint 21387139Smarkmring_empty_consecutive(Ring *ring) 21429088Smarkm{ 21529088Smarkm if ((ring->consume < ring->supply) || ring_empty(ring)) { 21629088Smarkm /* 21729088Smarkm * if consume is "below" supply, or empty, then 21829088Smarkm * return distance to the top 21929088Smarkm */ 22029088Smarkm return ring_subtract(ring, ring->top, ring->supply); 22129088Smarkm } else { 22229088Smarkm /* 22329088Smarkm * else, return what we may. 22429088Smarkm */ 22529088Smarkm return ring_subtract(ring, ring->consume, ring->supply); 22629088Smarkm } 22729088Smarkm} 22829088Smarkm 22929088Smarkm/* Return the number of bytes that are available for consuming 23029088Smarkm * (but don't give more than enough to get to cross over set mark) 23129088Smarkm */ 23229088Smarkm 23387139Smarkmint 23487139Smarkmring_full_count(Ring *ring) 23529088Smarkm{ 23629088Smarkm if ((ring->mark == 0) || (ring->mark == ring->consume)) { 23729088Smarkm if (ring_full(ring)) { 23829088Smarkm return ring->size; /* nothing consumed, but full */ 23929088Smarkm } else { 24029088Smarkm return ring_subtract(ring, ring->supply, ring->consume); 24129088Smarkm } 24229088Smarkm } else { 24329088Smarkm return ring_subtract(ring, ring->mark, ring->consume); 24429088Smarkm } 24529088Smarkm} 24629088Smarkm 24729088Smarkm/* 24829088Smarkm * Return the number of CONSECUTIVE bytes available for consuming. 24929088Smarkm * However, don't return more than enough to cross over set mark. 25029088Smarkm */ 25187139Smarkmint 25287139Smarkmring_full_consecutive(Ring *ring) 25329088Smarkm{ 25429088Smarkm if ((ring->mark == 0) || (ring->mark == ring->consume)) { 25529088Smarkm if ((ring->supply < ring->consume) || ring_full(ring)) { 25629088Smarkm return ring_subtract(ring, ring->top, ring->consume); 25729088Smarkm } else { 25829088Smarkm return ring_subtract(ring, ring->supply, ring->consume); 25929088Smarkm } 26029088Smarkm } else { 26129088Smarkm if (ring->mark < ring->consume) { 26229088Smarkm return ring_subtract(ring, ring->top, ring->consume); 26329088Smarkm } else { /* Else, distance to mark */ 26429088Smarkm return ring_subtract(ring, ring->mark, ring->consume); 26529088Smarkm } 26629088Smarkm } 26729088Smarkm} 26829088Smarkm 26929088Smarkm/* 27029088Smarkm * Move data into the "supply" portion of of the ring buffer. 27129088Smarkm */ 27287139Smarkmvoid 27387139Smarkmring_supply_data(Ring *ring, unsigned char *buffer, int count) 27429088Smarkm{ 27529088Smarkm int i; 27629088Smarkm 27729088Smarkm while (count) { 27829088Smarkm i = MIN(count, ring_empty_consecutive(ring)); 27981965Smarkm memcpy(ring->supply, buffer, i); 28029088Smarkm ring_supplied(ring, i); 28129088Smarkm count -= i; 28229088Smarkm buffer += i; 28329088Smarkm } 28429088Smarkm} 28529088Smarkm 28629088Smarkm#ifdef ENCRYPTION 28787139Smarkmvoid 28887139Smarkmring_encrypt(Ring *ring, void (*encryptor)(unsigned char *, int)) 28929088Smarkm{ 29029088Smarkm unsigned char *s, *c; 29129088Smarkm 29229088Smarkm if (ring_empty(ring) || ring->clearto == ring->supply) 29329088Smarkm return; 29429088Smarkm 29529088Smarkm if (!(c = ring->clearto)) 29629088Smarkm c = ring->consume; 29729088Smarkm 29829088Smarkm s = ring->supply; 29929088Smarkm 30029088Smarkm if (s <= c) { 30129088Smarkm (*encryptor)(c, ring->top - c); 30229088Smarkm (*encryptor)(ring->bottom, s - ring->bottom); 30329088Smarkm } else 30429088Smarkm (*encryptor)(c, s - c); 30529088Smarkm 30629088Smarkm ring->clearto = ring->supply; 30729088Smarkm} 30829088Smarkm 30929088Smarkm void 31029088Smarkmring_clearto(ring) 31129088Smarkm Ring *ring; 31229088Smarkm{ 31329088Smarkm if (!ring_empty(ring)) 31429088Smarkm ring->clearto = ring->supply; 31529088Smarkm else 31629088Smarkm ring->clearto = 0; 31729088Smarkm} 31829088Smarkm#endif /* ENCRYPTION */ 319